1. Technical Field
The present invention relates to push switches which are to be mounted mainly in automobiles and are utilized for manipulating various types of electronic devices.
2. Description of the Related Art
In recent years, generally, various switches have been mounted in interiors of automobiles, in order to enable to manipulate various types of electronic devices, such as room lamps and car audio apparatuses. As push switches for use thereas, there has been a need for push switches having smaller sizes and smaller thicknesses while being able to be certainly manipulated.
Such a conventional push switch will be described, with reference to FIGS. 4 to 6.
FIG. 4 is a cross-sectional view of the conventional push switch, and FIG. 5 is an exploded perspective view of the conventional push switch. Referring to FIG. 4 and FIG. 5, “1” designates a case having an opened upper surface and having a substantially-box shape, wherein the case is made of an insulating resin. “2” designates a common contact point made of a conductive metal, and “3” and “4” designate fixed contact points made of conductive metals. Common contact point 2 is secured to the left inner side wall of case 1 at its center portion, and fixed contact points 3 and 4 are secured thereto above and below common contact point 2, through insert molding and the like.
Further, “5” designates a manipulation member made of an insulating resin. “6” designates a cover made of an insulating resin. Cover 6 is adapted to cover the opening portion in the upper surface of case 1, and manipulation member 5 is housed within case 1 such that manipulation member 5 is movable upwardly and downwardly. Manipulation portion 5A at the upper end of manipulation member 5 is upwardly protruded, through an opening in the upper surface of cover 6.
Further, “7” designates a movable contact point formed from a conductive metal thin plate, wherein its center portion, its upper end and its lower end are in elastic contact with common contact point 2, pushing portion 5B in the left side surface of manipulation member 5 and fixed contact point 4, respectively, in a state where the movable contact point is slightly bent. This realizes a state where common contact point 2 and fixed contact point 4 are electrically connected to each other, through movable contact point 7.
Further, “8” designates a stopper with a substantially angular-U shape which is formed from a metal wire. Stopper 8 is engaged, at its upper end, in cam slot 5C with a substantially-heart shape which is formed in the right side surface of manipulation member 5, while the lower end of stopper 8 is hitched on the inner bottom surface of case 1.
Further, “9” designates a spring formed from a metal wire wound in a coil shape. Spring 9 is mounted between the lower end of manipulation member 5 and the inner bottom surface of case 1 or the lower end of stopper 8, in a state where spring 9 is slightly bent. This spring 9 biases manipulation member 5 upwardly, thereby forming the push switch.
Further, the push switch having the aforementioned structure is mounted in an automobile interior, in a state where a push button and the like are mounted on manipulation portion 5A. Further, the push switch is placed on a printed wiring board (not illustrated) having a plurality of wiring patterns formed on its upper and lower surfaces. Common contact point 2 and fixed contact points 3 and 4, which are protruded through the bottom surface of case 1, are soldered to predetermined wiring patterns and, thus, are electrically connected to an electronic circuit (not illustrated) in a vehicle or a device.
In the aforementioned structure, if manipulation portion 5A is pushed, manipulation member 5 moves downwardly in case 1 while bending spring 9, as illustrated in the cross-sectional view in FIG. 6. Pushing portion 5B presses the upper end of movable contact 7 and, thus, movable contact point 7 sways in the leftward and rightward directions, with common contact point 2 served as a fulcrum point. The lower end of movable contact point 7 is separated from fixed contact point 4, while the upper end of movable contact point 7 is brought into elastic contact with fixed contact point 3. This realizes a state where common contact point 2 is electrically connected to fixed contact point 3 through movable contact point 7.
Further, at the same time, the upper end of stopper 8 slides in cam slot 5C having a substantially-heart shape, while being in elastic contact therewith. If manipulation member 5 is moved downwardly by a predetermined distance, the upper end of stopper 8 is hitched in cam slot 5C, thereby realizing a state where manipulation member 5 is locked. The electronic circuit detects that common contact point 2 is being electrically connected to or separated from fixed contact points 3 and 4, thereby turning on a room lamp, for example.
Further, if manipulation portion 5A is pushed, again, to move manipulation member 5 downwardly by a predetermined distance, the upper end of stopper 8 slides in cam slot 5C while being in elastic contact therewith, thereby releasing the lock. Manipulation member 5 is upwardly biased by spring 9, which separates the upper end of movable contact point 7 from fixed contact point 3, thereby returning to the original state where the lower end of movable contact point 7 is in elastic contact with fixed contact point 4. The electronic circuit detects this, thereby realizing a state where the room lamp is extinguished, for example.
Namely, manipulation member 5 is moved upwardly and downwardly by being pushed, so that movable contact point 7 placed in the upward and downward direction, which is parallel with manipulation member 5, is swayed in the leftward and rightward directions with common contact point 2 served as a fulcrum point. This causes movable contact point 7 to bend, thereby bringing the upper and lower end thereof into elastic contact with one of fixed contact points 3 and 4. Thus, common contact point 2 is adapted to be electrically connected to or separated from fixed contact points 3 and 4, through movable contact point 7.
Further, as information about prior-art documents relating to the invention of the present application, Unexamined Japanese Patent Publication No. 2007-18790 has been known, for example.